A microprocessor device is a central processing unit or CPU for a data processing device which is usually contained in a single semiconductor integrated circuit "chip" fabricated by "MOS/LSI" technology. The term "microcomputer" will be used herein to refer to a microprocessor which may have on-chip memory for program and data storage. Modern microprocessors can be grouped into two general classes, namely general-purpose microcomputers and special-purpose microcomputers. Special-purpose microcomputers can be structured in such a manner that the performance of a specific function by the special-purpose microcomputers greatly exceeds the performance of the same function by a general-purpose microcomputer, regardless of the program created by the user.
One such function which can be performed by a special-purpose microcomputer at a greatly improved rate is digital signal processing. Digital signal processing applications, because of their computation intensive nature, also are rather intensive in memory access operations. The increasing demands of technology and the marketplace make desirable increased amounts of memory so that more complex functions and combinations of functions can be performed.
Among the objects of the present invention are to provide improved data processing devices that can address larger memory structures while maintaining high processing speeds. Another object of the present invention is to provide improved addressing with only minimal additional complexity in the data processing device, and to retain instruction code compatibility with an unimproved data processing device.
Other objects and advantages will be apparent to those of ordinary skill in the art having reference to the following figures and specification.